DETECTION OF BASAL ACETYLCHOLINE IN RAT-BRAIN MICRODIALYSATE

A liquid chromatography-electrochemistry (LC-EC) method is described f or the determination of basal acetylcholine (ACh) in microdialysate fr om the striatum of freely moving rats. This method is based on the sep aration of ACh and choline (Ch) by microbore liquid chromatography fol lowed by passage of the effluent through a post-column immobilized enz yme reactor (IMER), containing acetylcholinesterase (AChE) and choline oxidase (ChO), and then the electrochemical detection of the hydrogen peroxide produced. Instead of the conventional platinum electrode gen erally used for the anodic detection of hydrogen peroxide, a peroxidas e-redox polymer modified glassy carbon electrode operated at + 100 mV vs. Ag/AgCl has been used to detect the reduction of hydrogen peroxide . With this method, a detection limit of 10 fmol (injected) for ACh (S /N = 3:1) was obtained and the basal ACh concentration in striatal mic rodialysate was determined without using esterase inhibitors.